You and Your Trackwork ...
Getting To Know Each Other Better

In this first installment of Makin' Tracks, we're going to establish the language of trackwork which we will employ in future columns. As our readers come from a variety of railroading backgrounds, there may be different ways of expressing the items presented in this glossary. In our column I will be employing the terminology common to North American railroad practice and specifically that which is used by organizations such as the American Railroad Engineering Association (AREA), American Association of Railroads (AAR), and the U.S.Department of Transportation's Federal Railroads Administration (FRA). And as the column continues to develop, we will add various addenda to our glossary to keep your index up to date.

The following glossary provides through definitions and sketches a "from the ground up" foundation in trackwork terminology and will be useful for reference as we start Makin' Tracks in following editions. I have also provided a wide variety of References that will not only be used for sourcing technical and historical details, pictures, and other information in this column, but may be of general interest to our readers as well. Should anyone desire more information on any of these references please let me know and I will be glad to provide further details.

GLOSSARY OF TERMS

ALIGNMENT:

The horizontal location of a railroad as described by curves and tangents.

ANCHOR SPIKE:

A plate holding spike.

AUXILIARY FASTENINGS:

Tie plates, rail anchors, lock washers, and rail braces.

BALLAST:

Selected granular material placed on the roadbed for the purpose of holding the track in line and surface.

CANT:

The inward inclination of a rail, effected by the use of inclined surface tie plates, expressed as a rate of inclination, such as 1 in 40.

COMPOUND CURVE:

A horizontal curve in which the degree of curvature varies in different parts of the curve.

COMPROMISE JOINT:

A joint for uniting the abutting ends of rails of different cross section (for example an AREA 90 rail to an AREA 115 rail), or of rails of the same section but with different joint drilling patterns.

CONTINUOUS WELDED RAIL (CWR):

A number of rails welded together in lengths of 400 ft. or longer.

DERAIL:

A track structure designed to derail rolling stock in case of an emergency (say for example, a cut of cars rolling down an industrial spur to a mainline track would likely derail upon hitting the turnout at the mainline. A derail set ahead of this point would derail the cars before reaching the mainline reducing the risk of damage to mainline equipment and trackage).

SUPERELEVATION:

The vertical distance of the outer rail above the inner rail (banking on curves).

FASTENINGS:

Joint bars, bolts, and spikes or alternative hold down devices such as Pandrols or screws.

FIELD SIDE - GAUGE SIDE:

The field side of a rail is the face pointing away from the track or the outside face. The gauge side is the side of the rail which guides the wheel flange.

FROG:

A track structure used at the intersection of two running rails to provide support for wheels and passageways for their flanges, thus permitting wheels on either rail to cross over the rails (you'll see this again when we talk about turnouts and crossings).

GRADE:

The ratio of rise and fall of the grade line to its length (typically measured in percent grade. Say if a track is on a 1.5% grade, it rises 1.5 feet in every 100 feet of track. The maximum typical grade for railroad practice is on the order of 2% or 2 feet of rise in every 100 feet of track.

POINT OF SWITCH:

The end of the switch rail farthest from the frog. This is where the switch stand or operating mechanism moves the switch points to change switch position.

RAIL ANCHOR:

A device attached to the base of the rail designed to prevent it moving lengthwise on the ties.

REVERSE CURVE:

Two adjoining horizontal curves of opposite direction.

ROADBED:

The part of the roadway upon which the track structure is supported. I will also refer to this as the SUBGRADE of the track though the subgrade is really just the top surface of the roadbed which is below the ballast.

ROADWAY:

Includes in addition to the roadbed, the slopes of cuts, fill, ditches, access roads and other related works in the right of way.

SHOULDER:

The portion of roadbed and ballast which is between the end of the ties and the toe of the ballast slope.

SIMPLE CURVE:

A horizontal curve of uniform degree throughout the curve.

SUBBALLAST:

A select granular material which is used to separate the roadbed, or subgrade, from the crushed rock ballast.

TANGENT:

A straight track.

VERTICAL CURVE:

A special type of curve used to connect two different grades in the track.

Makin' Tracks | References